Apparatus for making sheet glass



@EST AVNLABLE COP.

Feb. 1 1927.

H. F. HITNER 7 APPARATUS FOR MAKING'SHEET GLASS Fild AuE. 20, 1925 3 Sheets-Sheet 1 I figw :3: M7

BEST AVAILABLE COP;

"H. F. HITNER APP ARATUS FOR MAKING SHEET GLASS Filed Aug. 20. 1925 3 Sheets-Sheets INVENTOR 'FJW 2 Ar .Twww

Patented Feb. 1, 1927.

. UNITED s'rA-Tss BEST AVAILABLE COP".

Par rear OFFICE.

HARRY F. EITHER, or rrr'rsnnnenl rnivNsYLvmrLA, ASSIGNOR "ro PITTSBURGH rLA'rn oLAss COMPANY, -A coRroRA'rIon or PENNSYLVANIA.

APPARATUS B MAKING SKEET'GLASS.

App1icatlon filed August 20, 1925. Serial No. 51,327.

The invention relates to apparatus for making glass 'in a continuous sheet or ribbon preferably by a draw-mg operation from a body of molten glass. It-has for its primary objects the provision of improved means for governing the temperature ofthe body of glass from which the sheet 15 generated, so that such temperature is under accurate control, and mav be maintained constant anduniform on the two sides of the sheet. One embodiment-of the invention is illustrated in the accompanying drawings wherein:

Figure 1 is a vertical section through the apparatus on the line I-II- .f of F1g. 3. Fig. 2' is a partial front elevation and pa rtial vertical section on the line 1IlI--II- 11-41 of Fig. 1. And Fig. 3 is a planview of the apparatus.

a melting tank preferably of the regenerator type having a forchearth or kiln from whic a continuous sheet of glass 3 is to -be drawn. Any desired form of drawing apparatus may be employed, the particular device illustrated comprising an annealin 'casing 4 divided into sections by means 0 the inclined partitions 5 and provided with a plurality o driven rolls 6 referably covered with asbestos and yieldingly engaging the opposite sides of the glass sheet, The glass pa'mingthrough the casin is gradually annealed and cooled an when it emerges at the top of the casing, it is cut into sections. This form of drawing apparatus is well known in the art and for that reason 1' uires no extended description. The fore earth or kiln 2 comprises an end wall 7, a pair of side walls 8, 8 and a bottom wall 9 of clay surrounded by in :sulating walls of siloeel or other similar material, such walls being designated by the reference numerals 1O, 11 and 12.-

Mounted in the glass bath of the kiln beneath the line of is a refractory gui e bar 13 for maintaining the locus of generation of the sheet substantially constant. .The kiln is provided with a cover in the form of a pair of blocks M and Iii-spaced apart to provide the opening "16 through which the sheet is drawn; A hock 17 is employed between the melting tr hand the kiln, such block extending down ii the glass bath and servin as a skim- {1 1;; devi nd also as a cut-o for prevent- 11 ,the h0t' gaaes in the melting furnace at- Referring to the-drawings, 1 is the end of of global.

eneration of the sheet feeting the glass bath in the kiln from' which the sheetis drawn, it bein desirable.

to eliminate in so far as is possib e any variations in the temperature conditions of the kiln incident to changes in term rature conditions or atmospheric conditions in the melting tank.

A plurality of sets of heating elements illustrated in the particular design of the drawings, there are four of these elements,

carried by the top members. 1ft and. 15 of the furnace and one each of such members'carried by the front, side and bottom walls of the kiln. Still another element is carried by a refractory tube extending transversely of the lgiln adjacent its outer, lower corner. These heating elements or rods may be composed of any one of the well-known refractory resistance compositions, the onepreferably used beinggcomposed largely of carborundum and known by the. trade name These heating elements are designated by the reference numerals 18, 19, 20, -21, 2-2, 23, 24, 25 and 26, and in each case, the element is made in two parts with the adjacent inner ends suitably supported," as a bar of this material of length sufficient" to extend from one side of the furnace'to the1S other requires support intermediate its en The elements 18, 19, 20 and 21 carried by the top members 1-1 and 15 heatthe glass di- ,rectly by radiation as they are relativel a flatsheet which is free from strain. ,The

sections'ot' the bars, as for instance, the bar "19 have their ends supported in the post 27 which has its side walls recessed to receive the ends of the sections and has its upper end connected to one of the electric terminals 28. This post is preferabl madeof a metal composition having hig Iheat reerablymade with the outer ends of the sections f-file resistance bar;l 13 b mgans g; ilk-s 11' has supporte y me ets .aiid b bnnected'to terminals 32. By this arjange'ment current 'may be supplied to the outer 'end'sof the sections from which it 1 asses through to the post 27 and out f'bugh the terminal 28. The sup orting 7 .-'brackets' for the terminals are prefera ly car- "'i'ied by the vertical sections 33, 34, 35, etc. whiclr are suitably connected by tie members and braces as illustrated. The resist- {J ance elements'22,.23 and 24 lie in passages "extending through the walls of the furnace and so ax-ranged that the surfaces of the bars are out of contact with the surroundin walls-ofithc passages. These bars are all made up of two pieces as described in connection with the bar 19 and they are sup ported at their inner ends by ascaloy posts and connected to suitable terminals at their outer ends, asillustratcd, and in the same manner as described in connection with the bar l9. These heating elements 22, 23, 2e and 25 are less direct in their eifect upon the glass than the elements 18, 19, 20 and 21, but

at the same time exert a substantial in- -fluence upon the glass'and tend to prevent devitrification of. the layer of glass lying close to thesidc walls of the kiln and which would otherwise have a temperature substantially lower than that of the body of glass-inzthekiln due to the conduction of the heatfrom this layer of glass by the clay walls. 4

' The heating element 26 is also similar in construction and support to that heretofore described in connection with the bar 19 and extends-transversely of the kiln from one side to the other. It is carried upon the interior of'thc hollow refractory member or .-tile 36.' ;This resistance clement exercises a=poweriui heating cll'cct upon the body of glass in the tank and tends to prevent any devitrification in the corner of the tank which is most liable to be subject to this ac: tion due to its-remoteness from the other .is jlittle, if any, circulation at this point tendin to distribute the stagnant glass --most liablc to become devitrified. Certain advantages are involved in spacing the ele- 5 meat 26 away from the walls of the hollow heating elements and to the fact that there 1,615,842 T VAILABLE COPY member 36. With the element 26 thus sup ported it is much easier to remove and rcplace it than if the surrounding material were in contact with it. Furthermore, the whole member 36 is subject to cracking due to expansion and contraction and such fraclure would, in most cases, crack the element 26 if the element were embedded in the member 36 withthe surfaces of the twothe use of temperature recording mstru ments, the drawing of the sheet may be conducted under temperature. conditions which have been found to produce the best results, and these conditions, "when once observed and determined, may be easilyreprodu'ced in the further operation of the apparatus. The fact that the forchcarth is 'cut bit fromthe influence of the melting tank to a large extent rcndcrs'this control definite, and reliable.

What I claim is:

1. The combination with container for molten glass, of heating means therefor comprising a tube of refractory material extending through the body of glass, :1 resistance rod extending throu ii the tube but out of contact therewith, an means for assing a current of electricity through sai rod.

2. The combination with container for molten glass, of heating means therefor comprising a tube of refractory material extend? ing through the body of glass, a. resistance rod egtten ing through the tube but out of contact therewith, and means for easing a current of electricity through said rod, the said rod being mounted so that it is free to movc'cndwlse. V

3. The combination with container for molten glasshaving walls of refractory niaterial with passages therethrough, of heatmg means therefor complrising resistance rods extending through t e passa es with their surfaces spaced away from t e walls of the passages, and means for passing a current of electricity through the rods. I

4C. The combination with container for molten glass, of side, bottom and end walls of refractory material with passages therethrough,0f heating means thereforcomprising resistance rods extending through the passages with their surfaces spaced away from the walls of the passages, and means for passing a current of electricity through the ro 5. The combination with container for molten glass, having walls of refractory material with passages thcrethrough, of heating means therefor comprising resistance rods.

extending through the passages with their surfaces spaced away from the walls of the passages, and means for passing a current of being made in two parts with supporting means at their meeting ends, and being free to move endwise. I

6. The combination with container for -molten glass having walls of refractory material with passages therethrough, of heating means therefor comprising resistance rods extending through the passe es with their surfaces spaced away from t e-walls of the passages, and means for passing a'current of electricity through the ,rods, each of the rods being made in two parts withsupporting means at their meeting ends, and having" yielding means for moving one of ,its parts endwise toward the other part.

7, The combination with a glass melting tank havinga drawing extension or kiln with a cover extending over the surface of.

the kiln and provided with a drawing'opening, of means for drawing a glass sheet upward through said opening, and means for heating the glass comprising a resistance rod spaced above the glass in the kiln below said coveroneach side of said drawing opening,

.and means for passing a current of electricit through said rods. 8. The combination'with a glass melting Loreen: v BEST AVAILA g, electricity through the rods, each of the rods tank, of a drawing extension or l tiln having walls of refractory material provided with passages, resistance rods extending through said passages, a refractory. tube extending through the body of glass in the tank,'a resistance rod extending throu h said tube,

meansfor causing a flow ofe ectric current through all of said rods, and means. for drawing a sheet of glass upwardly from the kiln.

- 9. The combination with a glass melting tank, of a drawingextension or kiln having walls of refractory material provided with passages, resistance rods extending through said passages, a refractory tube extending through the body of glass in the tank, a re I sistance rod extending through said tube,

a to for the kiln spaced "above 'the surface .of t e glass and havingfla drawing 0 ning,

a resistance rod extending across t e kiln between. the glass and the top on each -side of said drawing opening, and means for causin a flow of electric currentthrough all. 1

0f sai rods.

In testimony whereof, I have-hereunto subscribed my name this 18th day of July, 1925.

HARRY It. manna.- 

